There are two main figures that fit into this description:
William Walker gathered a group of people that were known as "the immortals". These were recruited by Walker, many of them were former mine workers. Together this group of people entered Nicaragua, that was in the midst of civil war. Thanks to his military victories, he later actually became elected president of Nicaragua.
The counterpart to him was Cornelius Vanderbril, As William Walker was doing all possible to maintain, he received military and economic aid from Byron Cole to retain his control of Nicaragua, the Latin American Allies were on their side working with Cornelius Vanderbilt a and finally were capable to dethrone the self-appointed “President of Nicaragua,” This ended American influence on the small country.
